Panel sanding apparatus



May .26, 1964 K. VEGSUND PANEL SANDING APPARATUS 3 Sheets-Sheet 1 FiledMarch 12, 1963 INVENTQR KARSTEN VEGSUND- ATTO R NEYS May 26, 1964 r K.VEGSUND 3,134,205

PANEL SANDING APPARAZIUS Filed March 12, 1965 3 Sheets-Sheet 2 INVENTORKARSTEN VEGSUNDv yd/409W 6 JG)? ATTORNE Y5- May 26, 1964 K. VEGSUND3,134,205

PANEL SANDING APPARATUS Filed March 12, 1963 s Sheets-Sheet 5 INVENTQHKARSTEN VEGSUND.

United States Patent 3,134,295 PANEL fiANDTNG ALPARATUS Karsten Vegsund,Burnaby, Eritish (Ioluinhia, Canada,

assignor to Canadian Forest Products Ltd, Vancouver,

British Columbia, Canada, a corporation of British Columbia Filed Mar.12, 1%3, her. No. 264,644 17 Claims. (Cl. 51-138) This invention relatesto apparatus for sanding panels that may have patches or otherirregularities projecting from the surface thereof, and particularly tosingle side sanding.

This apparatus is particularly designed for sanding the faces of plywoodpanels at or near the last stage of the manufacture of the plywood.During the manufacture of panels of a given thickness, say, for example,inch, the panels are of different thicknesses at this stage, and it isimportant to sand properly the faces thereof Without making the face plytoo thin or even going through the face ply. In the prior art, there aretwo methods of measuring or determining the amount of wood to be sandedoff each panel, namely, the fixed feed bed and the floating bed methods.The fixed feed bed method involves the establishment and maintenance ofa fixed thickness of any panel, and it is in effect sanding of the topface of the panel with reference to the bottom face thereof. Variationin the thickness of the panels arriving to be sanded results many timesin a major portion of the thickness of the face veneer and sometimesmore than the thickness of the face veneer being removed from the panel.This results in a high percentage of reject panels.

The floating bed method is one of sanding the face of the panel withreference to the top surface thereof. In other words, a predeterminedthickness of Wood is removed from the face veneer, and this is measuredfrom the outer surface down. In this method, the panel being sandedmoves over a floating bed or table. Pressure is applied to the uppersurface of the panel so as to depress the bed if the panel is thickerthan it should be. This method is not very successful for panels havingpatches or other irregularities in the face veneer thereof, or when thepanels vary considerably in thickness. These patches project slightlyabove the surface of the face veneer, and the projecting patches causethe bed to be depressed so that portions of the face are missed by thesander.

The present invention is an improvement of the floating bed method. Theapparatus includes means for pressing against the upper surface of apanel about to be sanded, but which is not influenced by a patchapproaching the sander, so that the sanding thicknes is not changed. Theapparatus may be set so that a predetermined number of patches which arealigned transversely of the direction of travel will not materiallyaffect the sanding thickness. However, if more than the predeterminedlaterally-aligned patches approach the sander or if the whole panel isoversized in thickness, the feed bed or table is depressed so that thesanding operation is affected in order not to damage the sanding tool bytoo many patches or not to sand too much off the surface in the case ofthe thick panels.

Apparatus according to the present invention comprises a sander, afloating table beneath the sander and over which a panel is moved alonga predetermined path with a face thereof exposed to said sander,adjustable loading means for urging the table upwardly towards thesander, an articulated shoe member mounted above the table immediatelyahead of the sander with reference to the direction of movement of apanel therebeneath, said shoe member including a plurality of shoesarranged side by side across said path and movable toward the table,individual pressure means for each shoe urging the latter downwardly,said shoes applying a force on each panel 3,3342% Fatented May 25., 1964ICC moving therebeneath against the loading of the table and saidloading means being set in order that a predetermined thickness issanded oif the panel as it moves beneath the sander, each shoe tendingto move upwardly when a patch moves therebeneath without raising theother shoes so that thedownward pressure on the table is not materiallyincreased by this patch and the sanding thickness is not disturbed.

The present invention is illustrated by way of example in theaccompanying drawings, in which:

FIGURE 1 is a diagrammatic plan view of the sanding apparatus, withparts of the sander thereof broken away,

FIGURE 2 is a section taken substantially on the line 2-2 of FIGURE 1,

FIGURE 3 is an enlarged fragmentary plan view of the shoe member of theapparatus,

FIGURE 4 is a cross section taken on the line 4-4 of FIGURE 3, and

FIGURE 5 is a fragmentary sectional View taken on the line 5-5 of FIGURE4.

Referring to the drawings, sanding apparatus 10 includes a floating bed12 resiliently and adjustably retained in different horizontal positionsby springs, fluid means or the like. In this example bed 12 is mountedon pneumatic or hydraulic cylinders 13, there being one of thesecylinders near each corner of the bed. The lower limit of movement ofbed 12 may be adjusted by means of screws 14. A table 18 is mounted onbed 12 and moves up and down therewith. In this example, the table is inthe form of an endless belt 26 rumiing around pulleys 21 and 22. Belt26' is horizontally arranged, and the upper run 24 thereof extends in asubstantially horizontal plane and forms the surface of table 18. Table18 is large enough to handle plywood panels and to move them in thedirection of arrow 26, shown in FTGURE 2.

A sander 3% is mounted above table 18 and positioned to sand the uppersurface of plywood panels as they move over the table. Any standardsander may be used for this purpose. In this example, sander 39 is inthe form of a sanding belt 32 extending around a large drum 33 and asmaller drum 34 mounted at opposite ends of arms 35 which are pivotallymounted on stub shafts 36 carried by suitable supports 37. The effectiveposition of sander 30 over table 18 is adjustable and maintained bymeans of a pneumatic or hydraulic cylinder 40 connected to one of thearms 35 through its projecting piston rod 41. A sanding drum may be usedinstead of the sanding belt without affecting the usefulness of thisinvention.

Belt table 18 is adapted to move plywood panels beneath sander 30, andthe path of travel is indicated by arrow 54 in FIGURE 2. Drum 33 isrotated by a suitable source of power, not shown, in the direction ofarrow 45 so that the portion of sanding belt 32 which comes into contactwith the upper surface of the plywood panels moves in the oppositedirection to the movement of said panels.

A fixed shoe 48 is carried by supports 37 and extends across table 18behind sander 3i) with reference to the direction of movement of thepanels along path 44. The lower surface of shoe 48 is in line with thesandingsurface of sander 30 so that said lower surface may ride lightlyon the sanded surfaces of the panels. The position of shoe 48 may beadjusted vertically in relation to the set position of the sandingsurface of sander 30, and its purpose is to guide the sanded panels andto prevent them from flapping as they clear the sander.

An articulated shoe member 52 extends above the surface of table 18across path 44 ahead of sander 3G with reference to the direction ofmovement of the panels and is suitably supported by supports 37. Thismember 52 is illustrated in detail in FIGURES 3 to 5.

Member 52 includes a bar 54 extending transversely relative to table 18and having a downwardly inclined upper surface 53 which enables the barto be fitted close to drum 33 without coming into contact with belt 32,as shown in FIGURE 2. Bar 54 also has an inner horizontal lower surface55 and an outer inclined lower surface 56. A plurality of shoes orplates 58 are arranged side by side beneath bar 54 and are carried bysaid bar. There are sufficient of these shoes or plates located side byside to cover the full width of the path of travel of the plywoodpanels. As shoes 58 are identical, only one will now be described indetail.

Shoe 58 is in the form of a plate having a horizontal inner section 61lying beneath bar inner surface 55, an outer inclined section 61overlying bar surface 56, and a vertical outer end 62 which extendsupwardly along the outer end surface 63 of the bar. It will be notedthat the entire shoe is spaced from bar 54, as indicated at 65 in FIGURE4. The shoe is resiliently urged to this spaced outer position, but itmay move upwardly towards bar 54. In this example, shoe 58 is carried.by a pair of inner bolts 67 which extend downwardly through bar 54 andthrough the horizontal inner section of the shoe. The head 58 of eachbolt is recessed in shoe section 65 so that its outer or lower surfaceis flush with the lower surface of said shoe, see FIGURE 4. A nut 69threaded on the upper end of each bolt 67 limits the downward movementof the shoe. A spring 70 on each bolt 67 positioned in a recess 71 inbar 54 extends between the shoe and the inner or upper end 72 of therecess and urges the shoe downwardly as far as the nuts 69 permit.Another bolt 75 extends downwardly through bar 54 near the inner tip 76of shoe 58, said bolt having a head 77 recessed in the inner horizontalsection 60 of the shoe. The upper end of bolt 75 extends into a recess79 opening out through the inclined surface 53 of bar 54, and has a nut59 threaded thereon which helps to limit the extent of movementdownwardly of shoe 58. A pair of springs 32 fit in sockets 33 formed inthe inner surface 55 of bar 54 and bear against the upper surface ofshoe section 60 to urge the shoe downwardly within the limit set by nuts65 and 80 on their respective bolts 6'7 and 75.

The outer end 62 of shoe 58 is provided with a hardened cup 8 5 whichopens inwardly towards bar 54 and carries a hardened ball 85 which bearsagainst a hardened wear strip 87 mounted on the outer end of surface 53of bar 54. This ball helps to position shoe 58 relative to bar 54 whilepermitting vertical movement of the latter. A guide bolt 90 is threadedinto the outer end 63 of bar 54 and extends through a vertical slot 92formed in the outer end 62 of the shoe. Bolt 90 is provided with ashoulder 93 which slidably fits in vertical slot 52 so as to preventshoe 58 from shifting laterally along bar 54 while permitting up anddown movement of the shoe.

The springs 70 and S2 of the shoes 58 are designed to exert apredetermined downward force against the shoes and, therefore, againstthe plywood panels moving under the shoes. This total downward force maybe adjusted within limits by means of nuts 65 and 85 on their bolts 67and 75. The more the nuts are tightened down on their bolts, the moreare these springs compressed, and therefore, the greater the downwardpressure against a panel moving under shoes 58 while raising said shoesand vice versa. It is obvious that springs 70 and 82 can be replaced bypneumatic or hydraulic pressure devices or cylinders.

Bar 54 with shoes 58 is adjustable vertically and is set so that whensander 30 is sanding a panel therebeneath, the actual sanding surface ofthe sander protrudes below the level of the horizontal inner sections6t) of the shoes. The extent of this protrusion equals the thickness ofpanel surface to be sanded off.

Standard air controls, not shown, are provided for air cylinders 13 ofthe floating bed 12 and table 18. This enables the operator to set thepressure in cylinder 13 so as to exert a predetermined upward forcethrough table .8

against the panels and against the downward thrust of shoes 58. When theapparatus is set to handle panels of a given thicknes, for example, 4inch panels, the pressure in air cylinders 13 is set so that sander 30will remove the predetermined thickness of wood from the upper surfaceof each panel, measuring downwardly from the upper surface of theunsanded panels over which shoes 58 ride. If a panel that is thickerthan usual enters the apparatus, there is a tendency to lift shoes 58,but the total spring load of these shoes is such that table 18 isdepressed so that the predetermined thickness of wood is sanded from theupper surface of the panel. Similarly, if a thinner panel than usualenters the apparatus, the pressure of air cylinders 13 will raise thepanel so that the same thickness is sanded off its upper surface.

One of the advantages of this apparatus results from the fact that aplurality of individual shoes 58 effect the downward force on the panelsinstead of a single shoe extending from side to side of the apparatus.By having an articulated shoe member, if there is a patch projectingfrom the upper surface of a panel, it will move under and raise one orat the most two shoes 58, thus increasing the downward pressure againstthe panel. However, this is not sufdcient to depress table 18 tomaterially change the thickness of the wood sanded off the panel. Thus,the patch and the require thickness of material are sanded off. Withoutthe articulated shoe member, the patch would tend to raise the entirepressure shoe thus lowering the floating bed and this would result inportions of the panel surface being missed altogether by the sander.

The spring loading of shoes 58 is such that if more than a predeterminednumber of these shoes are at the same time lifted higher than usual, thetable will be depressed and the patches will not be proprely sanded offso that it becomes a reject panel. It has been found that the pressurein air cylinders 13 and the springs 70 and 82 of the articulated shoemembers may be adjusted so that the raising of at least a given numberof shoes, say five shoes, increases the spring load against the panelenough to force the table to depress, whereas the raising of fourlaterally-aligned shoes will not increase the spring load against thepanel sufficiently to produce this result.

Thus it will be seen that the articulated shoe member makes it possibleto sand the surfaces of panels having patches protruding therefrom in afloating table machine without the patches affecting the operation ofthe sanding unless there are more than a predetermined number of patchesaligned transversely of the panel, in which case it usually is desirableto reject said panel.

What I claim as my invention is:

1. Sanding apparatus for wood panels, comprising a sander, a floatingtable beneath the sander and over which a panel is moved along apredetermined path with a face thereof exposed to said sander,adjustable loading means for urging the table upwardly towards thesander, an articulated shoe member mounted above the table immediatelyahead of the sander with reference to the direction of movement of apanel therebeneath, said shoe member including a plurality of shoesarranged side by side across said path and movable towards the table,and individual pressure means for each shoe urging the latterdownwardly, said shoes applying a force on each panel movingtherebeneath against the loading of the table and said loading meansbeing set in order that a predetermined thickness is sanded oif thepanel as it moves beneath the sander, each shoe tending to move upwardlywhen a patch or other irregularity protruding from the surface of thepanel moves therebeneath without raising the other shoes so that thedownward pressure on the table is not materially increased by one patchor irregularity and the sanding thickness is not disturbed.

2. Sanding equipment as claimed in claim 1 in which the loading means ofthe table is set so that a plurality of shoes above a predeterminednumber raised at the same time move the table downwardly.

Sanding equipment as claimed in claim 1 including means for adjustingthe individual pressure means ofeach shoe.

4. Sanding equipment as claimed in claim 1 in which the articulated shoemember comprises a bar mounted to extend across the panel path abovesaid path, and a plurality of plates forming the shoes independently andresiliently suspended from the bar, each plate extending beneath the barin the general direction of movement of the panels. 7

5. Sanding equipment as claimed in claim 4 in which the individualpressure means of each shoe plate is mounted on the bar and resilientlypresses against said plate to urge the latter to a normal positionspaced below the bar.

6. Sanding equipment as claimed in claim 4 in which each shoe plate issuspended from the bar about mid way between ends of the plate, andincluding guide means to limit lateral movement of the plate when itmoves towards and away from the table.

7. Sanding apparatus for wood panels, comprising a sander, a floatingtable beneath the sander and over which a panel is moved along apredetermined path with a face thereof exposed to said sander,adjustable loading means for urging the table upwardly towards thesander, a bar mounted above the table immediately ahead of the sanderwith reference to the direction of movement of a panel therebencath, aplurality of shoe plates arranged side by side across said path andspaced beneath the bar and above the table, means for suspending eachplate from the bar for movement towards and away from the bar, andindividual pressure means for each plate normally resiliently urgingsaid plate to a lowermost position above the table, said plates applyinga force on each panel moving therebeneath against the loading of thetable and said loading means being set in order that a predeterminedthickness is sanded oil the panel as it moves beneath the sander, eachplate tending to move upwardly when a patch or other irregularityprotruding from the surface of the panel moves therebeneath withoutraising the other plates so that the downward pressure on the table isnot materially increased by one patch or irregularity and the sandingthickness is not disturbed.

8. Sanding equipment as claimed in claim 7 in which each shoe plate iselongated and is suspended from the bar substantially mid way betweenends of the plate.

9. Sanding equipment as claimed in claim 8 in which each plate has ahorizontal section and an upwardly inclined section extending from thehorizontal section in the direction from which the panels travel towardsthe sander.

10. Sanding equipment as claimed in claim 8 in which each shoe plate hasa vertical end spaced from a vertical surface on the bar, a cup carriedby said vertical end and opening towards said vertical surface, and ahard ball in said cup-bearing against said vertical surface.

11. Sanding equipment as claimed in claim 10 in which the vertical endof the plate has a vertical slot therein, and including a pin projectingfrom the bar and extending through the slot, said pin preventing lateralmovement of the shoe plate,

12. In sanding apparatus for wood panels, an articulated shoe comprisingan elongated bar, a plurality of shoe plates arranged side by side, andspaced beneath the bar, means for suspending each plate from the bar formovement towards and away from the bar, and individual pressure meansfor each plate normally resiliently urging said plate to a lowermostposition relative to the bar.

13. Apparatus as claimed in claim 12 in which each shoe plate iselongated and is suspended from the bar substantially mid way betweenends of the plate.

14. Apparatus as claimed in claim 13 in which each plate has ahorizontal section and an upwardly inclined section extending away fromthe horizontal section.

15. Apparatus as claimed in claim 13 in which each shoe plate has avertical end spaced from a vertical surface on the bar, a cup carried bysaid vertical end and opening towards said'vertical surface, and a hardball in said cup bearing against said vertical surface.

16. Apparatus as claimed in claim 15 in which the vertical end of theplate has a vertical slot therein, and including a pin projecting fromthe bar and extending through the slot, said pin preventing lateralmovement of the shoe plate.

17. Sanding apparatus for wood panels, comprising a sander, a floatingtable beneath the sander and over which a panel is moved. along apredetermined path with a face thereof exposed to said sander,adjustable loading means for urging the table upwardly towards thesander, an articulated shoe member mounted above the table immediatelyahead of the sander with reference to the direction of movement of apanel therebeneath,

said shoe member including a plurality of shoes arranged side by sideacross said path and movable towards the table, and individual pressuremeans for each shoe urging the latter downwardly, said shoes bearingagainst the upper surface of each panel moving therebeneath over theupwardly-urged table and being normally positioned relative to thesander to permit a predetermined thiclmess of the panel to be sanded01f, and the pressure means of 'the shoes being such that when the panelthickness condition is such that there is a tendency to raise more thana predetermined number of shoes above said normal position, the combineddownward pressure of said latter shoes is sufilcient to cause the tableto be depressed.

References Cited in the file of this patent Schmutzler, Germanapplication 1,085,6S9,' printed July 21, 19601141. 38C 2/04).

12. IN SANDING APPARATUS FOR WOOD PANELS, AN ARTICULATED SHOE COMPRISINGAN ELONGATED BAR, A PLURALITY OF SHOE PLATES ARRANGED SIDE BY SIDE, ANDSPACED BENEATH THE BAR, MEANS FOR SUSPENDING EACH PLATE FROM THE BAR FORMOVEMENT TOWARDS AND AWAY FROM THE BAR, AND INDIVIDUAL PRESSURE MEANSFOR EACH PLATE NORMALLY RESILIENTLY URGING SAID PLATE TO A LOWERMOSTPOSITION RELATIVE TO THE BAR.